The present invention relates broadly to devices for cleaning windshields of rain and debris.
Although the wiping path varies by the make and model of vehicle, wiper blade assemblies are relatively consistent in construction, typically including an (a) elongated rubber element in the form of a scraper having a triangular cross section, (b) a metal strip called a flexor affixed along the backbone of the element, (c) a pair of claws designed to grasp the flexor, (d) a “superstructure” to which the claws are pivotably attached, and (e) an attachment point in the middle of the superstructure for affixing the entire wiper assembly to the wiper arm which is connected to a wiper motor. Presently all wiper blades attach to the middle of the superstructure. Although the so-called “Shepherd's Hook” type attachment is currently the industry standard, a number of alternatives are available and well known in the art.
Conventional windshield wiper blades suffer from checking and fault lines due to the motion imparted by the wiper arm and the constant flexing of the wiper blade material which tends to stress and eventually tear the wiper blade; usually away from the flexor. It is not uncommon to encounter a wiper blade torn longitudinally and flopping about during use. Both cold and heat may accelerate the degradation of the wiper blade; the cold rendering the material brittle and subject to cracking, and the heat speeding the decomposition of the polymer.
Of even greater concern than wiper degradation, is that the geometry of the wiper blade causes the wiper to scrape across the window, where grit and other abrasive debris may become trapped between the wiper blade and the windshield glass; resulting in scoring.
Some improvements to wiper blade geometry have been attempted; usually in the form of multiple blades in order to improve water removal. However, the multiple blade configuration simply exacerbates the issue of moving abrasive grit about the windshield surface. Regardless the coefficient of friction of the wiper material, because of the inherent geometry which is essentially that of a squeegee, grit and other debris eventually become trapped between the blade and the windshield glass.
Another concern with wiper blades is that even while the backbone allows for flexing of the blade to generally follow the contour of the windshield, windshield glass has many irregularities such as pocks and valleys that together shield debris from the blade edge.
What is needed is a wiper assembly that may be retrofitted onto existing wiper arms, and having a windshield surface contacting portion that rolls across the surface conforming to any surface irregularities, and so permitting the wiper assembly to remove grit and debris without scoring the glass.